Improvement in steam-engine side-valves



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IMPROVEMENT IN STEAM-ENGINE SLIDE-VALVES.

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T() ALL W IIOI IT MAY CONCERN:

Be it 1Known that I, ALFRED HOBBS, of Test Cambridge, in the county of Middlesex, and State of Massachusetts, have invented a new and improved Balanced Slide-Valve; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in the art to make and use the suine, reference being had to the accompanying drawings, forming part of this specification.

The object of my invention is to overcome the pressure of the steam Aupon the slide-valve of the steam engine; and the invention consists in forming the valve and valve-seat in a semicircular form, as will be hereinafter described.

Figure 1.1'cprcsents a plan or top view of my valve and seat partly in section, as through the line yy of fig. 2.

Figure f? is an end view, also partly in section, through the line :r of iig. 1.

Similar letters of reference indicate like parts.

o i Instead of constructing` my slide-valve in the usual ilat form, I make it circular, or nearly a halt` circle, with induction and ednction ports high up in the circle, by which means I balance, or nearly balance, the perpendicular' pressure of the steam upon the valve.

A represents the valve. B is the valve-seat. C represents the induction ports; and D the eduction or exhaust ports. E vshows the position of the valve-stem. In constructing the seat of the valve, the steam-chest is bored out the same as-though it were one entire cylinder7 and the valve is turned to fit the seat. There are ears cast on the valve for the purpose of centring it.

The valve operates the same as the common D-valvc, only there are two D-pockets, one on each side of the circle, for the exhaust, as seen in the drawing. In g. 1 the cylinder is taking steam at the left hand and exhausting at the right hand of the valve. The steam ports being so high up in the circle, they are nearly opposite each other, and consequently the pressure is nearly balanced. The actual downward pressure on the valve is ,very small, and only suiicient to keep it Well in its seat. By making the valve in this semicircular form I avoid the friction incident to the plug or tubular valve, which must'be packed or turned in tight enough to make a steam joint, thereby counteracting, by the friction thus occasioned, the benefits which would other- Wise be derived. v

I do not confine myself to the particular arrangement herein described. The position of the parts may be varied, and the same' or a similar counterbalaneing e`ect be obtained; but what I claim as new, and desire to secure by Letters Patent, is`

A semicircular balanced slide-valve, constructed and operating substantially as and for the purposes herein specified.

ALFRED HOBBS.

Witnesses:

G. W. HoBiis, J. C. HoBBs. 

